FIG. 3.

bba74 is expressed during nymphal feeding but not during murine infection. (A) qRT-PCR analysis of bba74, ospA, ospC, and ospE in flat and fed nymphal ticks and in murine hearts. RNAs used to generate cDNAs were obtained from pools of 150 flat or 30 fed B31-MI-infected nymphs at 72 h postattachment and from hearts isolated from three tick-infected C3H/HeJ mice at 17 days postattachment. Values represent the average copy number for each gene (± standard deviation) normalized per 100 copies of flaB. Statistical significance was determined using an unpaired t test; average values are considered significantly different when P is ≤0.05. The single asterisk (*), double asterisks (**), and pound symbol (#) indicate significantly different values for flat versus fed nymphs, flat nymphs versus murine tissue, and fed nymphs versus murine tissue, respectively. (B) Serological responses in mice 3 weeks following infestation with B31-MI-infected I. scapularis nymphs were assessed by immunoblot analysis using B31-MI whole-cell lysates (WCL) or purified recombinant (r) antigens. MW, molecular weight in thousands.